Fluid-filled structure

ABSTRACT

A fluid-filled chamber may include a pair of polymer layers that define a plurality of subchambers and a web area. The subchambers are protruding portions of the polymer layers that enclose a fluid, and the web area is portions of the polymer layers that are located between the subchambers and lay adjacent to each other. The subchambers may have greater thickness than the web area. A perimeter bond joining the polymer layers and extends around a periphery of the chamber. In addition, a plurality of interior bonds join the polymer layers and extend around the subchambers, which may seal the fluid within the subchambers.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.12/630,695, filed Dec. 3, 2009, the disclosure of which is incorporatedherein by reference in its entirety.

FIELD

The present disclosure relates generally to a fluid-filled structure,and more particularly to a chamber having a plurality of fluid-filledsubchambers.

BACKGROUND

Articles of footwear generally include two primary elements, an upperand a sole structure. The upper is formed from a variety of materialelements (e.g., textiles, foam, leather, and synthetic leather) that arestitched or adhesively bonded together to form a void on the interior ofthe footwear for comfortably and securely receiving a foot. Moreparticularly, the upper generally extends over the instep and toe areasof the foot, along the medial and lateral sides of the foot, under thefoot, and around the heel area of the foot. In some articles offootwear, such as basketball footwear and boots, the upper may extendupward and around the ankle to provide support or protection for theankle. Access to the void on the interior of the upper is generallyprovided by an ankle opening in a heel region of the footwear. A lacingsystem is often incorporated into the upper to adjust the fit of theupper, thereby permitting entry and removal of the foot from the voidwithin the upper. The lacing system also permits the wearer to modifycertain dimensions of the upper, particularly girth, to accommodate feetwith varying dimensions. In addition, the upper may include a tonguethat extends under the lacing system to enhance adjustability of thefootwear.

The sole structure is located adjacent to a lower portion of the upperand is generally positioned between the foot and the ground. In manyarticles of footwear, including athletic footwear, the sole structureconventionally incorporates a sockliner, a midsole, and an outsole. Thesockliner is a thin compressible member located within the void andadjacent to a lower surface of the void to enhance footwear comfort. Themidsole, which is be secured to a lower area of the upper and extendsdownward from the upper, forms a middle layer of the sole structure. Inaddition to attenuating ground reaction forces (i.e., providingcushioning for the foot), the midsole may limit foot motions or impartstability, for example. The outsole, which may be secured to a lowersurface of the midsole, forms the ground-contacting portion of thefootwear and is usually fashioned from a durable and wear-resistantmaterial that includes texturing to improve traction.

A variety of conventional midsoles incorporate a fluid-filled chamberthat increases durability of the footwear and further enhances theattenuation of ground reaction forces in the sole structure. In somefootwear configurations, the fluid-filled chamber may be at leastpartially encapsulated within a polymer foam material. In other footwearconfigurations, the fluid-filled chamber may substantially replace thepolymer foam material. That is, substantially all of the midsole or amajority of the midsole may be formed from the fluid-filled chamber. Ingeneral, fluid-filled chambers are formed from a polymer material thatis sealed and pressurized, but may also be substantially unpressurizedor pressurized by an external source. In some configurations, textile orfoam members may be located within the chamber, or reinforcingstructures may be bonded to an exterior surface of the chamber to impartshape to or retain an intended shape of the chamber.

Fluid-filled chambers may be manufactured through various processes,including a two-film technique, thermoforming, and blowmolding. In thetwo-film technique, two planar sheets of polymer material are bondedtogether in various locations to form the chamber. In order topressurize the chamber, a nozzle or needle connected to a fluid pressuresource is inserted into a fill inlet formed in the chamber. Followingpressurization, the fill inlet is sealed and the nozzle is removed.Thermoforming is similar to the two-film technique, but utilizes aheated mold that forms or otherwise shapes the sheets of polymermaterial during the manufacturing process. In blowmolding, a molten orotherwise softened elastomeric material in the shape of a tube (i.e., aparison) is placed in a mold having the desired overall shape andconfiguration of the chamber. The mold has an opening at one locationthrough which pressurized air is provided. The pressurized air inducesthe liquefied elastomeric material to conform to the shape of the innersurfaces of the mold, thereby forming the chamber, which may then bepressurized.

Although fluid-filled chambers may be utilized in footwear, variousconfigurations of the fluid-filled chambers may also be utilized inother products. For example, fluid-filled chambers may be incorporatedinto backpack straps, golf clubs, and cushions.

SUMMARY

Various fluid-filled chambers are discussed below. In one configuration,a chamber includes a pair of polymer layers that define a plurality ofsubchambers and a web area. The subchambers are protruding portions ofthe polymer layers that enclose a fluid, and the web area is portions ofthe polymer layers that are located between the subchambers and layadjacent to each other. The subchambers may have greater thickness thanthe web area. A perimeter bond joining the polymer layers and extendsaround a periphery of the chamber. In addition, a plurality of interiorbonds join the polymer layers and extending around the subchambers,which may seal the fluid within the subchambers.

Various methods for manufacturing chambers are discussed below. In oneexample, the method includes molding a first polymer layer and a secondpolymer layer to define a plurality of protrusions. A first bond isformed between the first polymer layer and the second polymer layer, andthe first bond extends around a periphery of the chamber. A fluid isinjected between the first polymer layer and the second polymer layer,and the fluid enters the protrusions. Additionally, a plurality ofsecond bonds are formed between the first polymer layer and the secondpolymer layer, and the second bonds extend around each of theprotrusions to seal the fluid within the protrusions.

The advantages and features of novelty characterizing aspects of theinvention are pointed out with particularity in the appended claims. Togain an improved understanding of the advantages and features ofnovelty, however, reference may be made to the following descriptivematter and accompanying figures that describe and illustrate variousconfigurations and concepts related to the invention.

FIGURE DESCRIPTIONS

The foregoing Summary and the following Detailed Description will bebetter understood when read in conjunction with the accompanyingfigures.

FIG. 1 is lateral side elevational view of an article of footwear.

FIG. 2 is a medial side elevational view of the article of footwear.

FIG. 3 is a cross-sectional view of the article of footwear, as definedby section line 3 in FIG. 2.

FIG. 4 is a perspective view of a chamber from the article of footwear.

FIG. 5 is a top plan view of the chamber.

FIG. 6 is a side elevational view of the chamber.

FIGS. 7A-7C are cross-sectional views of the chamber, as respectivelydefined by section lines 7A-7C in FIG. 5.

FIGS. 8A-8K are top plan views corresponding with FIG. 5 and depictingfurther configurations of the chamber.

FIGS. 9A-9E are cross-sectional views corresponding with FIG. 7A anddepicting further configurations of the chamber.

FIG. 10 is a perspective view of a molding tool.

FIGS. 11A-11C are side elevational views of a molding process thatutilizes the molding tool in the manufacture of the chamber.

FIGS. 12A-12C are cross-sectional views of the molding process, asrespectively defined by section lines 12A-12C in FIGS. 11A-11C.

FIG. 13 is a perspective view of material forming the chamber followingthe molding process.

FIG. 14 is a perspective view of a inflate-bond tool.

FIGS. 15A-15C are side elevational views of a bonding and inflationprocess that utilizes the bond and inflate tool in the manufacture ofthe chamber.

FIGS. 16A-16C are cross-sectional views of the bonding and inflationprocess, as respectively defined by section lines 16A-16C in FIGS.15A-15C.

FIG. 17 is a cross-sectional views corresponding with FIG. 16A anddepicting another configuration of the bonding and inflation process.

DETAILED DESCRIPTION

The following discussion and accompanying figures disclose variousconfigurations of fluid-filled chambers and methods for manufacturingthe chambers. Although the chambers are disclosed with reference tofootwear having a configuration that is suitable for running, conceptsassociated with the chambers may be applied to a wide range of athleticfootwear styles, including basketball shoes, cross-training shoes,football shoes, golf shoes, hiking shoes and boots, ski and snowboardingboots, soccer shoes, tennis shoes, and walking shoes, for example.Concepts associated with the chambers may also be utilized with footwearstyles that are generally considered to be non-athletic, including dressshoes, loafers, and sandals. In addition to footwear, the chambers maybe incorporated into other types of apparel and athletic equipment,including helmets, gloves, and protective padding for sports such asfootball and hockey. Similar chambers may also be incorporated intocushions, backpack straps, golf clubs, and other compressible structuresutilized in household goods and industrial products. Accordingly,chambers incorporating the concepts disclosed herein may be utilizedwith a variety of products.

General Footwear Structure

An article of footwear 10 is depicted in FIGS. 1-3 as including an upper20 and a sole structure 30. For reference purposes, footwear 10 may bedivided into three general regions: a forefoot region 11, a midfootregion 12, and a heel region 13, as shown in FIGS. 1 and 2. Footwear 10also includes a lateral side 14 and a medial side 15. Forefoot region 11generally includes portions of footwear 10 corresponding with the toesand the joints connecting the metatarsals with the phalanges. Midfootregion 12 generally includes portions of footwear 10 corresponding withthe arch area of the foot, and heel region 13 corresponds with rearportions of the foot, including the calcaneus bone. Lateral side 14 andmedial side 15 extend through each of regions 11-13 and correspond withopposite sides of footwear 10. Regions 11-13 and sides 14-15 are notintended to demarcate precise areas of footwear 10. Rather, regions11-′13 and sides 14-15 are intended to represent general areas offootwear 10 to aid in the following discussion. In addition to footwear10, regions 11-13 and sides 14-15 may also be applied to upper 20, solestructure 30, and individual elements thereof.

Upper 20 is depicted as having a substantially conventionalconfiguration incorporating a plurality material elements (e.g.,textiles, foam, leather, and synthetic leather) that are stitched oradhesively bonded together to form an interior void for securely andcomfortably receiving a foot. The material elements may be selected andlocated with respect to upper 20 in order to selectively impartproperties of durability, air-permeability, wear-resistance,flexibility, and comfort, for example. An ankle opening 21 in heelregion 13 provides access to the interior void. In addition, upper 20may include a lace 22 that is utilized in a conventional manner tomodify the dimensions of the interior void, thereby securing the footwithin the interior void and facilitating entry and removal of the footfrom the interior void. Lace 22 may extend through apertures in upper20, and a tongue portion of upper 20 may extend between the interiorvoid and lace 22. Given that various aspects of the present discussionprimarily relate to sole structure 30, upper 20 may exhibit the generalconfiguration discussed above or the general configuration ofpractically any other conventional or non-conventional upper.Accordingly, the overall structure of upper 20 may vary significantly.

Sole structure 30 is secured to upper 20 and has a configuration thatextends between upper 20 and the ground. In addition to attenuatingground reaction forces (i.e., providing cushioning for the foot), solestructure 30 may provide traction, impart stability, and limit variousfoot motions, such as pronation. The primary elements of sole structure30 are a midsole 31, an outsole 32, a sockliner 33, and a chamber 40.Midsole 31 is secured to a lower area of upper 20 and may be formed fromvarious polymer foam materials (e.g., polyurethane or ethylvinylacetatefoam) that extend through each of regions 11-13 and between sides 14 and15. Additionally, midsole 31 at least partially envelops or receiveschamber 40, which will be discussed in greater detail below. Outsole 32is secured to a lower surface of midsole 31 and may be formed from atextured, durable, and wear-resistant material (e.g., rubber) that formsthe ground-contacting portion of footwear 10. Sockliner 33, as depictedin FIG. 3, is located within a lower portion of the void in upper 20 andis positioned to contact a plantar (i.e., lower) surface of the foot toenhance the comfort of footwear 10. In addition to these elements, solestructure 30 may incorporate one or more support members, moderators, orreinforcing structures, for example, that further enhance the groundreaction force attenuation characteristics of sole structure 30 or theperformance properties of footwear 10.

When incorporated into sole structure 30, chamber 40 has a shape thatfits within a perimeter of midsole 31 and extends through heel region 13and a portion of midfoot region 12, and also extends from lateral side14 to medial side 15. Although chamber 40 is depicted as being entirelyencapsulated within the polymer foam material of midsole 31, chamber 40may be exposed on either of sides 14 and 15 in some configurations offootwear 10. When the foot is located within upper 20, chamber 40extends under the foot in order to attenuate ground reaction forces thatare generated when sole structure 30 is compressed between the foot andthe ground during various ambulatory activities, such as running andwalking. In some configurations, chamber 40 may protrude outward frommidsole 31, may extend further into midfoot region 12, may extendforward to forefoot region 11, or may be solely located in forefootregion 11. In other configurations, chamber 40 may form a portion of anupper surface or a lower surface of midsole 31, chamber 40 may bepositioned to form the ground-contacting portion of footwear 10, chamber40 may form substantially all of midsole 31, or may be located withinsockliner 33. Accordingly, the shape and dimensions of chamber 40, aswell as the position of chamber 40 within footwear 10, may varysignificantly.

Chamber Configuration

Chamber 40 is depicted individually in FIGS. 4-7B and is formed from afirst layer 41 and a second layer 42. Each of layers 41 and 42 aremolded or otherwise shaped to define various fluid-filled subchambers 43that are separated and interconnected by a web area 44. Layers 41 and 42are bonded or joined together in various locations to form (a) aperipheral bond 45 around a periphery of chamber 40 and (b) a pluralityof interior bonds 46 around each of subchambers 43.

Layers 41 and 42 form opposite sides of chamber 40 and cooperativelydefine portions of subchambers 43 and web area 44. More particularly,opposite sides of each subchamber 43 are formed from layers 41 and 42,and opposite sides of web area 44 are also formed from layers 41 and 42.As oriented in the various figures, first layer 41 forms an upperportion of chamber 40, whereas second layer 42 forms a lower portion ofchamber 40. In other configurations, this orientation may be reversedsuch that layers 41 and 42 respectively form the lower and upperportions of chamber 40. Although peripheral bond 45 is depicted as beingcentrally-located between upper and lower portions of chamber 40,peripheral bond may also be off-set from the center, which may enhancethe aesthetics of chamber 40.

A wide range of polymer materials may be utilized for layers 41 and 42.In selecting a material for layers 41 and 42, the ability of thematerial to prevent the diffusion of the fluid contained by each ofsubchambers 43 may be considered, as well as the engineering propertiesof the material (e.g., tensile strength, stretch properties, fatiguecharacteristics, dynamic modulus, and loss tangent). When formed from apolymer material, layers 41 and 42 may have a thickness of approximately1.0 millimeter, but the thickness may range from 0.25 to 4.0 millimetersor more, for example, depending upon the specific polymer materialutilized. Examples of thermoplastic polymer materials that may besuitable for layers 41 and 42 include urethane, polyurethane, polyester,polyester polyurethane, and polyether polyurethane. Various thermosetpolymer materials may also be utilized for layers 41 and 42. Morespecific examples of materials that may be utilized for layers 41 and 42include the various materials disclosed in any of (a) U.S. Pat. Nos.4,183,156, 4,219,945, 4,936,029, and 5,042,176 to Rudy; (b) U.S. Pat.Nos. 5,713,141 and 5,952,065 to Mitchell, et al.; and (c) U.S. Pat. Nos.6,013,340, 6,082,025, 6,127,026, 6,203,868, and 6,321,465 to Bonk, etal.

Subchambers 43 exhibit a generally spherical shape and are distributedthroughout chamber 40. As discussed above, layers 41 and 42cooperatively define opposite sides or portions of subchambers 43. Moreparticularly, each of layers 41 and 42 form various hemispherical areas(i.e., protrusions/indentations in layers 41 and 42) that cooperativelyimpart the spherical shapes to each of subchambers 43 when combined.Each of subchambers 43 have a generally hollow configuration thatencloses a fluid (e.g., a gas, liquid, gel). Interior bonds 46 extendaround subchambers 43 to prevent the fluid from escaping chamber 40 orpassing between subchambers 43, thereby isolating subchambers 43 fromfluid communication with each other. The fluid within subchambers 43 maybe pressurized between zero and three-hundred-fifty kilopascals (i.e.,approximately fifty-one pounds per square inch) or more. In addition toair and nitrogen, the fluid may include any of the gasses disclosed inU.S. Pat. No. 4,340,626 to Rudy.

Although subchambers 43 have similar shapes, the overall size or volumeof subchambers 43 may vary significantly. For example, subchambers 43located in heel region 13 exhibit a generally larger diameter, volume,or size than subchambers 43 located in midfoot region 12. Similarly,subchambers 43 located in a peripheral area of chamber 40 (i.e.,adjacent to peripheral bond 45) exhibit a generally larger diameter,volume, or size than subchambers 43 located in a central area of chamber40. This configuration places larger subchambers 43 under the heel ofthe foot and at the periphery of the foot.

Web area 44 extends between and generally interconnects the varioussubchambers 43. Whereas subchambers 43 protrude outward to formstructures for receiving the fluid within chamber 40, web area 44exhibits lesser thickness and forms portions of layers 41 and 42 thatare adjacent to each other and may lay in contact with each other.Although some of subchambers 43 are immediately adjacent to othersubchambers 43, a portion of web area 44 is generally located betweenadjacent subchambers 43, thereby extending between interior bonds 46 ofthe adjacent subchambers 43. Referring to the cross-sectional views ofFIGS. 7A-7C, for example, the amount of web area 44 between adjacentsubchambers 43 may vary considerably. In some areas of chamber 40,subchambers 43 exhibit a thickness or overall height that is ten times athickness or height of web area 44. In general, however, the thicknessof subchambers 43 ranges from three to greater than ten times thethickness of web area 44. In the areas between subchambers 43, web area44 generally lays parallel to a plane of chamber 40 and does not includestructural elements, such as fluid communication passages.

Peripheral bond 45 and interior bonds 46 form areas of chamber 40 wherelayers 41 and 42 are secured, bonded, or otherwise joined to each other.Peripheral bond 45 extends around the periphery of chamber 40, therebyjoining layers 41 and 42 at the periphery. Similarly, interior bonds 46extend around each of subchambers 43, thereby joining layers 41 and 42at edges of each subchamber 43. Whereas peripheral bond 45 is primarilylocated at an edge of chamber 40, interior bonds 46 are primarilylocated at an interior of chamber 40. In areas where subchambers 43 arelocated at the periphery of chamber 40, however, interior bonds 46coincide or otherwise overlap with peripheral bond 45. Although web area44 may extend between adjacent interior bonds 46, as depicted in FIGS.7A and 7C, two interior bonds 46 may effectively overlap betweensubchambers 43 that are immediately adjacent to each other, as depictedin FIG. 7B.

An advantage to chamber 40 relates to flexibility. More particularly,the configuration of web area 44 enhances the overall flexibility ofchamber 40. In some fluid-filled structures, conduits or fluidcommunication passages extend between subchambers in order to transferfluid to the subchambers during the manufacturing process. In chamber40, however, conduits and fluid communication passages are absentbetween subchambers 43. That is, the manufacturing process for chamber40, which is discussed in greater detail below, does not rely uponconduits to transfer fluid to the various subchambers. As a result,conduits and other molded structures are absent from web area 44, whichincreases the flexibility of web area 44, thereby increasing the overallflexibility of chamber 40.

Another advantage to chamber 40 relates to the configurability of thecompressibility of each subchamber 43. In general, the compressibilityof an individual subchamber 43 depends upon various factors, including(a) the thickness of layers 41 and 42 forming the subchamber 43, (b) thepressure of the fluid within the subchamber 43, and (c) the diameter oroverall volume of the subchamber 43. By varying any of these factors,the compressibility of the individual subchamber 43 may be modified.More particularly, the compressibility may be increased by (a)decreasing the thickness of layers 41 and 42, (b) decreasing thepressure of the fluid, or (c) increasing the diameter or overall volume.Similarly, the compressibility may be decreased by (a) increasing thethickness of layers 41 and 42, (b) increasing the pressure of the fluid,or (c) decreasing the diameter or overall volume. By varying thesefactors throughout chamber 40, the compressibility of particular areasof chamber 40 may be configured for particular uses of chamber 40. Asdiscussed in greater detail below, each of these factors may be modifiedduring the manufacturing process of chamber 40.

The configuration of chamber 40 discussed above provides one example ofa suitable configuration for use in footwear 10 and other products. Avariety of other configurations may also be utilized. For example, theoverall shape of chamber 40 may vary to include a circularconfiguration, as depicted in FIG. 8A, or a triangular configuration, asdepicted in FIG. 8B, each of which may be suitable for a variety ofproducts. Other shapes specifically adapted for footwear, such asfootwear 10, may also be used, as in the shoe outline shape depicted inFIG. 8C. Although subchambers 43 may be positioned as depicted in FIG.5, a more regular spacing may also be utilized. Referring to FIG. 8D,subchambers 43 are positioned in rows and columns and spaced from eachother. A similar configuration is depicted in FIG. 8E, whereinsubchambers 43 contact or are placed in relative proximity to adjacentsubchambers 43. FIGS. 8D and 8E also depict a configuration wherein thediameters or volumes of the various subchambers 43 are substantiallyidentical. The shapes of subchambers 43 may also vary significantly toinclude hexagonal, square, varied, and irregular shapes, as depicted inFIGS. 8F-8I. In some configurations, web area 44 may be partiallyremoved to form apertures extending through chamber 40, as depicted inFIG. 8J. Similarly, web area 44 may be entirely removed to form aplurality of discrete or separate structures formed from subchambers 43,as depicted in FIG. 8K. Accordingly, a variety of features relating tothe shape of chamber 40, the positions, spacing, and shapes ofsubchambers 43, and the configuration of web area 44, for example, maybe modified depending upon the intended use or purpose of chamber 40.

In addition to the variations discussed above with respect to FIGS.8A-8K, further variations are depicted in FIGS. 9A-9E. Referring to thecross-sectional views of FIGS. 7A and 7C, layers 41 and 42 are spacedfrom each other in web area 44. If, for example, some of the fluidutilized to fill or pressurize subchambers 43 is present in web area 44,layers 41 and 42 may separate. In some configurations, however, layers41 and 42 may contact each other in web area 44, as depicted in FIG. 9A.Similarly, layers 41 and 42 may be bonded to each other in web area 44,as depicted in FIG. 9B. Although the portions of subchambers 43 that areformed from layers 41 and 42 may be similarly-shaped, these portions mayalso have different configurations. Referring to FIG. 9C, for example,first layer 41 forms semicircular areas for chambers 43, wherein secondlayer 42 is planar. Layers 41 and 42 may also form structures ofdifferent size, as depicted in FIG. 9D, or with different shapes, asdepicted in FIG. 9E. Accordingly, a variety of additional featuresrelating to chamber 40 may be modified depending upon the intended useor purpose of chamber 40.

Chamber Manufacturing

In manufacturing chamber 40, two general processes are utilized: amolding process and an inflation and bonding process. In general, themolding process involves shaping of layers 41 and 42, and may alsoinvolve bonding layers 41 and 42 to form peripheral bond 45. Theinflation and bonding process involves inflating or pressurizingsubchambers 43 and bonding layers 41 and 42 to form interior bonds 46.Each of these processes will be discussed in greater detail below.

A molding tool 50 is depicted in FIG. 10 as having a first mold portion51 and a second mold portion 52. Mold portions 51 and 52 cooperativelydefine an internal cavity where layers 41 and 42 are molded to exhibitthe general shape of chamber 40. More particularly, mold portions 51 and52 each form various indentations 53 that correspond in location andsize with subchambers 43, and mold portions 51 and 52 each define aperipheral ridge 54 that corresponds in location with peripheral bond45. In other configurations, mold portions 51 and 52 may cooperativelydefine two internal cavities, one having the configuration of chamber40, which is suitable for footwear 10 when configured for the right footof the wearer, and the other having the configuration of a mirror imageof chamber 40, which is suitable for footwear 10 when configured for theleft foot of the wearer.

The manner in which molding tool 50 is utilized to form chamber 40 fromlayers 41 and 42 will now be discussed in greater detail. Initially,layers 41 and 42 are positioned between mold portions 51 and 52, asdepicted in FIGS. 11A and 12A. At this stage of the molding process,layers 41 and 42 are planar sheets of a polymer material that have notbeen molded or otherwise shaped. A plurality of conduits may extendthrough molding tool 50 in order to channel a heated liquid, such aswater or oil, through molding tool 50, thereby raising the overalltemperature of molding tool 50. When layers 41 and 42 are positionedwithin molding tool 50, heat may be transferred from molding tool 50 tolayers 41 and 42 in order to raise the temperature of layers 41 and 42.At elevated temperatures that depend upon the specific polymer materialutilized, layers 41 and 42 soften or become more deformable, whichfacilitates shaping and bonding. In some manufacturing processes,various conductive or radiative heaters may be utilized to heat layers41 and 42 prior to placement within molding tool 50 in order to decreasemanufacturing times.

Once layers 41 and 42 are positioned between mold portions 51 and 52,mold portions 51 and 52 translate toward each other such that layers 41and 42 enter the internal cavity within molding tool 50 and are shaped,as depicted in FIGS. 11B and 12B. As molding tool 50 contacts andenvelops portions of layers 41 and 42, a fluid (e.g., air) having apositive pressure in comparison with ambient air may be injected betweenlayers 41 and 42 to induce layers 41 and 42 to respectively contact andconform to the contours of mold portions 51 and 52 (i.e., enterindentations 53). Air may also be removed from the area between layers41 and 42 and mold portions 51 and 52 through various vents, therebydrawing layers 41 and 42 onto the surfaces of mold portions 51 and 52.That is, at least a partial vacuum may be formed between layers 41 and42 and the surfaces of mold portions 51 and 52. As the area betweenlayers 41 and 42 is pressurized and air is removed from the area betweenmolding tool 50 and layers 41 and 42, layers 41 and 42 conform to theshape of molding tool 50. More specifically, layers 41 and 42 stretch,bend, or otherwise conform to extend along the surfaces of indentations53 within molding tool 50 and form the general shape of chamber 40.

In addition to shaping layers 41 and 42, mold portions 51 and 52compress layers 41 and 42 together at locations corresponding withperipheral ridges 54, thereby forming peripheral bond 45. When exposedto sufficient heat, the polymer materials of layers 41 and 42 transitionfrom a solid state to either a softened state or a semi-liquid state,particularly when a thermoplastic polymer material is utilized. Whensufficiently cooled, the polymer materials then transition back from thesoftened state to the solid state. Based upon these properties ofpolymer materials, bonding processes may be utilized to form a bond thatjoins portions layers 41 and 42. As utilized herein, the term “bonding”or variants thereof is defined as a securing technique between twoelements that involves a softening or melting of a polymer materialwithin at least one of the elements such that the materials of theelements are secured to each other when cooled. Similarly, the term“bond” or variants thereof is defined as the bond, link, or structurethat joins two elements through a process that involves a softening ormelting of a polymer material within at least one of the elements suchthat the materials of the elements are secured to each other whencooled. Bonding may occur when only one of layers 41 and 42 includes apolymer material or when both of layers 41 and 42 include polymermaterials. Additionally, bonding does not generally involve the use ofadhesives, but involves directly bonding layers 41 and 42 to each otherwith heat. In some situations, however, adhesives or other securingtechniques may be utilized to supplement peripheral bond 45.

Layers 41 and 42 both form portions of subchambers 43 and web area 44.The thickness of layers 41 and 42 prior to molding may be greater thanthe thickness of layers 41 and 42 in the resulting chamber 40. Therationale for the difference in thickness between layers 41 and 42 isthat the polymer material forming layers 41 and 42 may stretch duringthe thermoforming process. That is, the thickness differences compensatefor thinning in layers 41 and 42 that occurs when layers 41 and 42 arestretched or otherwise deformed during the formation of subchambers 43and web area 44.

Once layers 41 and 42 are shaped within molding tool 50, mold portions51 and 52 separate such that layers 41 and 42 may be removed frommolding tool 50, as depicted in FIGS. 11C and 12C. Layers 41 and 42 arethen permitted to cool. Referring to FIG. 13, which depicts layers 41and 42 following the molding process, a channel 47 is formed in layers41 and 42. Referring to FIG. 10, at least first portion 51 is depictedas including a channel 55 extending from areas forming the internalcavity. During the molding process discussed above, channel 55 formschannel 47 in at least first layer 41. As discussed with respect to thebonding and inflation process below, channel 47 may be utilized toinject the fluid into chamber 40.

Based upon the discussion above, the molding process forms a structurethat is similar to chamber 40. Although the shape of subchambers 43 areformed in layers 41 and 42 and peripheral bond 45 is formed, layers 41and 42 are not bonded to form interior bonds 46. As a result, bonds orother structures joining layers 41 and 42 are absent in areas locatedinward from peripheral bond 45. Additionally, excess portions of layers41 and 42 may remain secured to the portions forming chamber 40, andchannel 47 is formed in the excess portions. Despite the formation ofperipheral bond 45, a gap or separation may be present between theportions of layers 41 and 42 forming subchambers 43 and web area 44, asdepicted in FIG. 12C. That is, layers 41 and 42 may be spaced from eachother in areas located inward from peripheral bond 45

Although the molding process discussed above is a suitable manner ofshaping layers 41 and 41 during the manufacture of chamber 40, ablowmolding process may also be utilized. In general, a suitableblowmolding process involves positioning a parison between a pair ofmold portions, such as mold portions 51 and 52. The parison is agenerally hollow and tubular structure of molten polymer material. Informing the parison, the molten polymer material is extruded from a die.The wall thickness of the parison may be substantially constant, or mayvary around the perimeter of the parison. Accordingly, a cross-sectionalview of the parison may exhibit areas of differing wall thickness.Suitable materials for the parison include many of the materialsdiscussed above with respect to layers 41 and 42. Following placement ofthe parison between the mold portions, the mold portions close upon theparison and pressurized air within the parison induces the liquefiedelastomeric material to contact the surfaces of the mold. In addition,closing of the mold portions and the introduction of pressurized airinduces the liquefied elastomeric material to contact the surfaces ofthe mold portions. Air may also be evacuated from the area between theparison and the mold portions to further facilitate molding and bonding.Accordingly, layers 41 and 42 may also be formed through a blowmoldingprocess. As a further alternative, a conventional rotational moldingprocess may be utilized to form layers 41 and 42.

Once the molding process is complete, the inflation and bonding processmay be utilized to inflate subchambers 43 and form interior bonds 46. Ainflate-bond tool 60 is depicted in FIG. 14 as having a first portion 61and a second portion 62. Portions 61 and 62 cooperatively define aninternal cavity having the general shape of chamber 40. Moreparticularly, portions 61 and 62 each (a) form various indentations 63that correspond in location and size with subchambers 43 and (b) definea interior ridges 64 that extend around indentations 63 and correspondin location with interior bonds 46. Additionally, at least portion 62includes an inflation connector 65 that interfaces with channel 47. Inother configurations, portions 61 and 62 may cooperatively define twointernal cavities, one having the configuration of chamber 40, which issuitable for footwear 10 when configured for the right foot of thewearer, and the other having the configuration of a mirror image ofchamber 40, which is suitable for footwear 10 when configured for theleft foot of the wearer.

The manner in which inflate-bond tool 60 is utilized to continue formingchamber 40 will now be discussed in greater detail. Initially, themolded structure formed from layers 41 and 42 using molding tool 50 ispositioned between portions 61 and 62, as depicted in FIGS. 15A and 16A.Additionally, an end of channel 47 is joined with inflation connector65. At this stage of the process, layers 41 and 42 are generally moldedto define semi-circular protrusions corresponding with subchambers 43.Layers 41 and 42 are also bonded together to form peripheral bond 45,and channel 47 provides a fluid inlet to the area between layers 41 and42.

Once the molded layers 41 and 42 are positioned between portions 61 and62, portions 61 and 62 translate toward each other such that layers 41and 42 enter the internal cavity within inflate-bond tool 60, asdepicted in FIGS. 15B and 16B. As inflate-bond tool 60 contacts andenvelops the molded structure formed from layers 41 and 42, a fluid(e.g., a pressurized fluid or a fluid at ambient pressure) is injectedthrough inflation connector 65 and into channel 47. The fluid thenpasses into the area between layers 41 and 42 that forms chamber 40. Asthe area between layers 41 and 42 is pressurized, radio frequencybonding may be utilized to form interior bonds 46. In other words, radiofrequency energy that causes layers 41 and 42 to heat and bond may passthrough inflate-bond tool 60, particularly at interior ridges 64. Giventhat layers 41 and 42 may be formed from a thermoplastic polymermaterial, the increased temperature causes the polymer material to meltor soften, thereby inducing bonding between layers 41 and 42. That is,the radio frequency energy passes through layers 41 and 42 at interiorridges 64 and causes layers 41 and 42 to bond with each other in areascorresponding with interior bonds 46.

As noted above, the inflation and bonding process involves inflatingsubchambers 43 and bonding layers 41 and 42 to form interior bonds 46.While positioned within inflate-bond tool 60, fluid is first injectedinto the area between layers 41 and 42 through inflation connector 65and channel 47. Injecting the fluid effectively pressurizes the areascorresponding with subchambers 43. Once properly pressurized, the radiofrequency energy forms interior bonds 46, thereby sealing thepressurized fluid within subchambers 43. Some of the pressurized fluidmay also remain in web area 44, which causes layers 41 and 42 to bowoutward slightly. In some configurations, however, the pressurized fluidmay be allowed to exit web area 44. In other configurations ofinflate-bond tool 60, conductive heating, adhesive joining, or otherbonding techniques may be utilized to form interior bonds 46.

Once inflation and bonding are complete, portions 61 and 62 separatesuch that chamber 40 and other portions of layers 41 and 42 may beremoved from inflate-bond tool 60, as depicted in FIGS. 15C and 16C.After proper cooling, the excess portions of layers 41 and 42 may betrimmed at peripheral bond 45 and recycled, thereby substantiallycompleting the manufacture of chamber 40.

The procedures discussed above impart a configuration wherein each ofsubchambers 43 are pressurized to substantially the same pressure.Various techniques may be utilized, however, to pressurize subchambers43 differently. Referring to FIG. 17, inflate-bond tool 60 has aconfiguration wherein the centrally-located indentations 63 aretruncated or otherwise not large enough to accommodate the semi-circularprotrusions in layers 41 and 42, whereas the peripherally-locatedindentations 63 have the same shape as the protrusions in layers 41 and42. When layers 41 and 42 enter inflate-bond tool 60, the truncatedindentations 63 compress the protrusions to reduce the volume in thecentrally-located subchamber 43. Once pressurized and removed frominflate-bond tool 60, the pressure in the centrally-located subchamber43 will be less than the pressure within other subchambers 43.Accordingly, the pressure of subchambers 43 may be controlled orotherwise modified by decreasing the volume of indentations 63 ininflate-bond tool 60.

Another method of varying the pressures within subchambers 63 is toutilize a two-stage bonding process. For example, the area betweenlayers 41 and 42 may be pressurized to a first pressure and then some ofinterior bonds 46 are formed. The area between layers 41 and 42 may thenbe pressurized to a second pressure and the remainder of interior bonds46 are formed. In this manner, some of subchambers 43 will bepressurized to the first pressure and some will be pressurized to thesecond pressure. Two inflate-bond tools 60 may be utilized in atwo-stage bonding process to form the various interior bonds 46, but asingle inflate-bond tool 60 that selectively forms interior bonds 46 mayalso be utilized.

The invention is disclosed above and in the accompanying figures withreference to a variety of configurations. The purpose served by thedisclosure, however, is to provide an example of the various featuresand concepts related to the invention, not to limit the scope of theinvention. One skilled in the relevant art will recognize that numerousvariations and modifications may be made to the configurations describedabove without departing from the scope of the present invention, asdefined by the appended claims.

What is claimed is:
 1. A sole structure including a fluid-filledchamber, the fluid-filled chamber comprising: a first polymer sheet; asecond polymer sheet attached to the first polymer sheet and cooperatingwith the first polymer sheet to define molded regions respectivelydefining a plurality of protrusions; a first bond formed between thefirst polymer sheet and the second polymer sheet and extending around aperiphery of the chamber; and a plurality of second bonds formed betweenthe first polymer sheet and the second polymer sheet to form a web arealocated between the protrusions, the second bonds completely surroundingeach of the protrusions to seal and pressurize a fluid within theprotrusions; wherein the first polymer sheet and the second polymersheet remain spaced apart from each other in unbonded portions of theweb area between the protrusions, the unbonded portions having adifferent shape than the protrusions; wherein a thickness of the chamberin the web area is less than a thickness of the chamber at theprotrusions; and wherein the plurality of protrusions include a firstseries of protrusions located along a medial side of the chamber, asecond series of protrusions located along a lateral side of thechamber, and a third series of protrusions located between the firstseries of protrusions and the second series of protrusions and beingsmaller than the first series of protrusions and the second series ofprotrusions, the unbonded portions being disposed between the firstseries of protrusions and the third series of protrusions and beingdisposed between the second series of protrusions and the third seriesof protrusions and including a substantially uniform size and shape ateach location of the unbonded portions.
 2. The sole structure of claim1, wherein the fluid is pressurized.
 3. The sole structure of claim 2,wherein the protrusions are operable to receive the fluid afterformation of the first bond and before formation of the second bonds. 4.The sole structure of claim 1, wherein the protrusions are operable toreceive the fluid after formation of the first bond and before formationof the second bonds.
 5. The sole structure of claim 1, wherein theplurality of protrusions include a substantially spherical shape.
 6. Thesole structure of claim 1, wherein the fluid within the protrusionsdefines a fixed volume.
 7. An article of footwear comprising: a solestructure including a fluid-filled chamber, the fluid-filled chambercomprising: a first polymer sheet; a second polymer sheet attached tothe first polymer sheet and cooperating with the first polymer sheet todefine molded regions respectively defining a plurality of protrusions;a first bond formed between the first polymer sheet and the secondpolymer sheet and extending around a periphery of the chamber; and aplurality of second bonds formed between the first polymer sheet and thesecond polymer sheet to form a web area located between the protrusions,the second bonds completely surrounding each of the protrusions to sealand pressurize a fluid within the protrusions; wherein the first polymersheet and the second polymer sheet remain spaced apart from each otherin unbonded portions of the web area between the protrusions, theunbonded portions having a different shape than the protrusions; whereina thickness of the chamber in the web area is less than a thickness ofthe chamber at the protrusions; and wherein the plurality of protrusionsinclude a first series of protrusions located along a medial side of thechamber, a second series of protrusions located along a lateral side ofthe chamber, and a third series of protrusions located between the firstseries of protrusions and the second series of protrusions and beingsmaller than the first series of protrusions and the second series ofprotrusions, the unbonded portions being disposed between the firstseries of protrusions and the third series of protrusions and beingdisposed between the second series of protrusions and the third seriesof protrusions and including a substantially uniform size and shape ateach location of the unbonded portions.
 8. The article of footwear ofclaim 7, wherein the fluid is pressurized.
 9. The article of footwear ofclaim 8, wherein the protrusions are operable to receive the fluid afterformation of the first bond and before formation of the second bonds.10. The article of footwear of claim 7, wherein the protrusions areoperable to receive the fluid after formation of the first bond andbefore formation of the second bonds.
 11. The article of footwear ofclaim 7, wherein the plurality of protrusions include a substantiallyspherical shape.
 12. The article of footwear of claim 7, wherein thefluid within the protrusions defines a fixed volume.